class Age():
    def __get__(self, instance, owner):
        print(self)
        print(instance)
        print(owner)
        print('====')
        print('__get__')
        
        pass
    def __set__(self, instance, value):
        print(value)
        print('__set__')
        pass
    def __delete__(self, instance):
        print('__delete__')
        pass

class Person():
    age = Age()
    def __init__(self, age) -> None:
        self._age = age


print(Person.age)
Person.age = 19    
del Person.age
# 只有 get方法是有用的，可见，只有 

# def Person.age
